Read the following information carefully and answer the questions which follow:
(i) ′A×B′ means A is the son of B.
(ii) ′A+B′ means A is the father of B.
(iii) ′A>B′ means A is the daughter of B.
(iv) ′A<B′ means A is the wife of B.
What will come in place of question mark (?), if it is provided that M is the grandmother of F in the expression, ′F×R<S?M′?